Fourth to thomas henry lee bake



(No Model.)

H. A. LEVERETT. PROCESS OF AND APPARATUS FOR TANNING.

No. 542,680. Patented July'ls, 1895.

Q x L IIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIII NlTE TATE-S HENRY ALFREDLEVERETT, OF LONDON, ENGLAND, ASSIGNOR FOURTH TO THOMAS I-IENRY LEEBAKE, OF SAME PLACE.

PROCESS OF AND APPARATUS FOR TANNING.

SPECIFICATION forming part of Letters Patent No. 542,680, dated July 16,1895.

Application filed August 28,1894. sedan). 521,494. (No as.

To all whom it may concern:

Be it known that I, HENRY ALFRED LEVER- ETT, a subject of the Queen ofGreat Britain,

residing at London, in'the county of Middlesex, England, have inventedcertain new and useful Improvements in Tanning Skins and Hides; and I dohereby declare that the following is a full, clear, and exactdescription of the invention, which will enable others skilled in theart to which it appertains to make and use the same.

This invention relates to the application of currents of hydrogen gas orany suitable gaseous compound of same in which arsenic is present, ashydrogen arsenide, which is caused at intervals to pass through thetanning liquor in the pit or vessel containing the hides or skins to betanned. By this action the process of tanning is greatly expedited, andat the same time superior qualities of leather are produced at a cheaprate.

The invention is specially applicable. to open tanning-pits; but thepits may, if desired, be provided with covers for temporary closing, itit is intended to save some of the hydrogen gas and lead it back "to thegas-holder for further use, instead of letting it escape in the air fromthe open pit. The intermittent admissions of the gas may beadvantageously efiected by adjustable automatic appliances. The hydrogengas may advantageously be produced by the aid of sulphuric acid ofcommerce acting on ordinary zinc or iron, or by passing steam through aretort containing pieces of iron or other suitable material.

When the hydrogen is produced by either of the two methods referred to,it will take up the arsenical impurities in the metals, which aregenerally present in sufficient quantity to insure a proper proportionof arsenic in the gas. The arsenic acts as an antiseptic and tends toprevent the decomposition of the tanning agent, which is of greatimportance. I have found that hydrogen is the only gas which does notdetrimentally affect the tanning liquor, the tanning agent (tannic acid)being decomposed or converted into gallic acid .by those gaseous bodiesor compounds heretofore employed, as nitrogen, or compounds of nitrogen,as air, or carbonicacid gas. Furthermore, the hydrogen acts as a vehiclefor the tannin and carries it over and through the hides and keeps thepores open, and serves also to agitate the liquor. The hydrogen may, ofcourse, be produced by electrolysis; but this would be objectionable onthe score of expense.

' The proportion of arsenic in the hydrogen arsenide will, of course,vary according to the nature of the hides to be tanned, a meanproportion being about two milligrams of arsenic to ten liters ofhydrogen.

The accompanying drawing illustrates one suitable mode, out of many, forcarrying the invention into effect, being a vertical section through apit and appurtenances thereto.

The pipe A from the hydrogen-generator conveys the gas to the store orgas-holder B, and the gas is, by a pipe 0, led to asmaller gas-holder D,and-thence by a pipe E to the lower part of tanning-pits F, containingthe hides or skins, which may suitably be suspended from rods orcross-bars G. Taps or valves A, G, and E are provided to regulate theadmission of the gas. I

The gas from the generator is admitted to the gas-holder B, the bell ofwhich is suitably weighted or loaded to the required pressure. Gas isadmitted from it to the smaller gasholder D, which may be adapted insize for a number of tan-pits, and has its bell suitably weighted forthe pressure required to drive the gas through the liquor in the pit orpits without causing the liquor to flow over or splash over. By the useof the smaller gasholder D an even and adjustable pressure of the gasadmitted to the tan-pitsis insured, In this invention it is consideredadvantageous to use one large or a fewlarge tanpits rather than a numberof small pits, as now usual, and indeed necessary, because of theperiodical handling of the skins. This handling is in this inventiondispensed with. The tap E (or taps, if a number of pits are used) havingbeen opened, the gas flows into the lower part of the pit F,distributing itself into a nest of pipes H inthe lower part of the pitand, issuing from tine holes in the said pipes, passes up through thespaces between the skins, thereby agitating the liquor and" passing offinto the air at the open pit (or, if desired, when the cover K is put onand the too weight of the bell of the gas-holder B has been suitablyrelieved. the gas is made to return to the gas-holder B) through asuitable valved pipe (shown in dotted lines in the drawing) andconnecting the gas-holder or coverK with the pipe 0 on the inlet side ofvalve 0. The hydrogen is admitted for the space ofa minute or a fewminutes only at a timethat is to say, at intervals of say one to fourhours, all according to the nature of the hides and the class of leatherto be produced. An unduly lengthened or continuous action of the gas isdetrimental and produces harsh or hard leather.

In some cases it is advisable to suspend for a day or more theperiodical admission of the gas, in order to prevent the grain of thehides from being unduly hardened.

The length-of time of admission is or may be efiected by the apparatusitself, if the cubic contents of the gas-holders and the tanpits areproperly proportioned, WVhen the valve or tap 0 between the twogas-holders is closed, and the tap or taps E to the tan pit or pits areopened, the gas in the gas-holder D will flow into the pit or pits untilits power to pass up through the liquor is equaled by the resistance ofthe liquor, and will thus cease of its ownaccord. The action will notcommence again until the gas-holder D is recharged with sufficientgas-pressure from the gas-holder B. The periodical opening and closingof the tap 0 between the two gasholders B and D may be'efiected eitherby hand or automatically by means of suitable machinery. This machinerymay be' clockwork or anyother motor drivinga shaft, so as to ma t tevery o ly to p n; nd

h y u ta tepp s or o r vices th said valve 0' at the required intervalsand for the space of time required, or the valve 0 may be made tocontrol so small an opening that it takes from, say, one to four hoursto recharge the gas-holder D, the time being determined by giving one ormore turns to the valve-spindle, which is formed with a very finescrew-thread accordingly-say, for instance, one turn in opening thevalve repree senting four hours to recharge; two turns,

three hours, and so on.

Any other suitable self-acting means may be applied for carrying out thepurpose in view. Instead of the valve (3, or in addition thereto, aself-acting automatic, plessurefreducing valve may be provided betweenthe two gas-holders, so as to prevent the pressure in the gas-holder Dfrom rising above a fixed maximum. The admission from the gas: holder Dto the tan-pits may then be eflected by means of taps or valves actuatedby automatic machinery, as above described, and either to open and closesimultaneously for all the pits, or for one after the other.

The action of the hydrogen has the effect of shortening the period oftanning skins and hides to such an extent that even those of thicksubstance may be tanned in a comparav ly sho im while (and th s is a ryportant feature or result of this invention) the fiber strength, thequality, the color, and,

the appearance of the leather are equal to those'of the leather producedby the ordinary a ng p e s of m y mont rat o also by this process isavoided the so-called handling of. the skins, which involves much timeand labor, and a great saving in tanning material is ef ected. I

Having fully described my invention, what I desire to claim and secureby Letters Patnt s 1. The improvement in the process of tanning hidesand skins, consisting in passing a gaseous compound consisting in partof hydrogen arsenide at intervals through the tanning liquor in the pitor vessel containing the hides and skins to be tanned, substantially asset forth.

2- T mp vem n in he process o nning hides and skins, consisting inpassing hydrogen containing hydrogen arsenide at automatically regulatedintervals through the tanning liquor in the pit or vessel containing thehides and skins to be tanned, substantially as set forth.

3. In a tanning apparatus, the combination with a pit provided withasuitable cover, a support from which the hides or skins may be'suspe dednd a per o a d p p a the bottom of said pit, of a main gas holder, anauxiliary g s h lder of redetermine capacity, a pipe connecting the mainand auxiliary gas holders, a pipe .connecting the last named l er 't afoe ai perf r te pip an means for controlling the flow of gas through saidpipes, for the purpose set forth.

4. In a tanning apparatus, the combination with a pit, a support fromwhich the hides or sk ns may e. suspe ded, a: perforated pipe. at thebottom of the pit, a gas collector covr ng e mo h o s 'p t, d a n g sholder and a pipe connection between the same and the aforesaid gascollector, of an auxiliary gas holder of predetermined QrLP Q' ity, pipeconnections between the main and auxiliary gas holders and between thelatter and the aforesaid perforated pipe, and means for controlling theflow of gas through the pipe connections, for the purpose set forth.

5. In combination with apit adapted to contain tanning liquor, of adevice for distributing gas through the liquor in said pit, a gasholder, and suitable connections therewith, an intermediate pressurechamber between said gas holder and distributing device, and a gascollector over said pit with pipe connections to the gas holder,substantially as described. 6. In combination with a tanning pit adaptedto contain tanning liquor, of a device for distributing gas through theliquor in said pit, together with a gas holder, suitable connectionsbetween the device and holder, an intermediate pressure chamber, andmeans for regulating the flow of gas from the gas holder to the pressurechamber and from the pressure chamber to the distributing device,substantially as described.

7. In combination with a pit adapted to 5 contain tanning liquor, ofperforated pipe at the bottom of the pit, and a removable gas collectoradapted to close the mouth of said pit, a source of gas supply, pipeconnections between the latter and the system of perforated pipe andsaid gas collector, and means to for controlling the flow of gas to andfrom said source of supply, substantially as described.

HENRY ALFRED LEVERETT.

Witnesses:

O. A. JENSEN, T. F. BARNES.

